The authors report the case of a 69-year old female with a persistent history of low back pain. Plain lumbar radiographs, performed at symptom initiation, revealed lumbar spondylolisthesis. Low back pain was attributed to this, and the patient received conservative treatment with partial relief of symptoms. Four years later, and as a result of acute onset of radicular symptoms, a lumbar spine magnetic resonance imaging scan was performed, revealing an epidural cystic lesion. The cyst was removed, and histopathology revealed a synovial cyst.